Thermal processing torches, such as plasma arc torches, are widely used in the heating, cutting, gouging, and marking of materials. A plasma arc torch generally includes an electrode, a nozzle having a central exit orifice mounted within a torch body, electrical connections, passages for cooling, and passages for arc control fluids (e.g., plasma gas). A swirl ring can be used to control fluid flow patterns in the plasma chamber formed between the electrode and the nozzle. In some torches, a retaining cap can be used to maintain the nozzle and/or swirl ring in the torch body. In operation, a plasma arc torch produces a plasma arc, which is a constricted jet of an ionized gas with high temperature and sufficient momentum to assist with removal of molten metal. Power used to operate plasma arc torches can be controlled by a power supply assembly of a plasma operating system. The power supply can include a plurality of electronic components configured to control and supply an operational current to the plasma arc torch, the gas flows provided to the plasma arc torch, and, in some cases, motion of the plasma arc torch.
During a cutting sequence, a plasma jet is used to first pierce through a workpiece to form an initial pilot hole. The pilot hole typically must be formed before the torch can be moved to form the cut. Conventional systems are typically unable to determine how long it actually takes for the plasma jet to fully pierce a workpiece. Therefore, empirical data is used to determine a conservative time estimate in which worn consumables could fully perform the piecing operation. As a result of these conservative time estimates, plasma jets are commonly held in place for more time than needed to pierce the workpiece, which can result in lost processing time, unnecessary electrode wear, and potential workpiece warping or damage.
Some systems are configured to implement certain gas or electrical parameters during start up or shut down based on desired characteristics of the arc during use. For example, some systems, upon intentional extinguishing of the plasma arc, can provide desirable gas flow or current profile combinations for shut down.
Typically, after prolonged use, consumables, such as electrodes, can physically degrade and begin to mechanically break down due to heat and pressure. In some cases, electrodes can undergo catastrophic failure, which can be referred to as a complete blowout in which molten metal portions of the consumable may flow back into the torch clogging passageways, unintended component arcing may occur, and/or the electrode can break apart and be expelled into the torch. Such actions can cause damage to the torch.